OOPSLA Java VM panel notes

Bill Huey billh at mag.ucsd.edu
Sat Oct 24 13:23:46 PDT 1998

> One question was whether people would be writing their JIT compilers
> and VMs in Java itself, bootstrapping. Someone at Sun said a bit about
> OpenJIT, a self-compiling Java JIT written in Java. They're hoping to
> release it to the public, if Sun's lawyers will allow them.

It's probably going to be useless to folks like us.

> David Ungar made a comment that processors are getting faster for
> math, but not really for OO programming. He says contemporary

That's because he probably can't write in assembler and because
his also on *Crack*.

Modern processors are plenty fast enough for OO. You just have 
to glue the appropriate compiler technology to it and do live variable
analysis, basic block evalution, code motion, inlining etc.

> architectures are not agile enough, comparing them to dragsters that
> are super fast but can't turn.

That's bullshit.

Things like boundary check of arrays can be completely pipelined out by
the CPU, method caching, inlining of small methods.

Static compilers are going to do some interesting things in the future
probably much more so that any JIT.

There are issues such as garbage collection speed, message passing etc...
that need to be addressed.

But I think it's going to have good results regardless of what that
guy says.

> I asked a question to the panel about open source JVMs. I commented
> that the lack of an open source JavaVM was hindering research and
> wondering whether anyone on the panel thought that an open source VM
> was important. David Ungar said that no one on the panel could help,
> "because we've all sold out". Much laughter. David Ungar didn't sound
> terribly sympathetic to the open source issue, although folks in the
> crowd seemed to be.

That a really unfortunate attitude.

The HotSpot technology isn't that unique since many dynamic recompilation
technologies such as FX!32 are just reiteration of standard compiler
theory that you can get out of the Dragon book, etc...

I'm personally looking forward to see what people can do with stati compilers.


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